Influence of atomised powder characteristics on texture and microstructuredevelopment in extruded A1-8Fe-4Ni base alloys

The texture and microstructure of as-extruded Al-7.7Fe-4Ni and Al-8.2Fe-4.3 Ni-2.8Zr (wt.%) alloys reinforced by large volume fractions (> 30 vol.%) of coherent intermetallics was studied. It is shown that the texture and micr ostructure developed in the as-extruded alloys is very sensitive to charact eristics of the rapidly solidified powders. In particular, variations in po wder microstructure and associated hardness are responsible for heterogeneo us deformation which leads to the formation of a banded structure consistin g of alternate coarse and fine microstructure characterised by a major [111 ] fibre texture of the Al-matrix. This texture of the Al-matrix is coupled to a texture of the coherent intermetallic phase. On contrast. more homogen eous deformation results in a more homogeneous microstructure with fairly r andom texture for both the Al and tau phases. (C) 1999 Elsevier Science S.A . All rights reserved.